Zack Wheeler #45 of the New York Mets stands on...

Zack Wheeler #45 of the New York Mets stands on the mound in the second inning against the Oakland Athletics at Citi Field on Wednesday, June 25, 2014 in the Queens Borough of New York City. Jim McIsaac Credit: Jim McIsaac

The Mets already traded Zack Wheeler once during his rehab from Tommy John surgery in last year’s failed deal for Carlos Gomez. But as the front office explores ways to improve their vulnerable lineup, and Wheeler inches toward a mid-July return, don’t expect it to happen again in the weeks ahead.

As one source explained Saturday, the Mets have “close to zero interest” in using Wheeler as trade bait, despite his potential value in helping upgrade the offense. In the closing minutes before last year’s deadline, Sandy Alderson caved to swapping Michael Fulmer, the organization’s top pitching prospect, for Yoenis Cespedes because the Tigers flatly refused to take anyone else.

This time, however, the Mets view Wheeler as an integral part of their second-half plans, whether it’s going to a six-man rotation to keep their starters fresh for the late September push or moving one to the bullpen. Adding Wheeler to the already stacked rotation seems like bringing sand to the beach. But after Steven Matz again complained of left elbow tightness following Saturday night’s ugly 4-3 loss to the Braves, the Mets might need the insurance.

Matz downplayed the elbow discomfort, saying it’s been “off and on” and “during the season, you go through these things.” For someone like Matz, however, who’s already had Tommy John surgery, any elbow-related twinges can be anxiety-provoking. And reason enough to hold tight to Wheeler.

Before Saturday, the Cubs’ rotation led the majors with a 2.29 ERA, followed by the Mets (3.19), Nationals (3.29) and Giants (3.36). Problem is, the Mets were supposed to possess the starting edge over everyone else in baseball. And without that significant advantage, their run-production issues become more glaring.

The gap between the Mets’ proficiency on the mound and at the plate has been too wide. Their .722 OPS ranked ninth in the NL before Saturday, but their .236 batting average was 12th and only two teams had scored fewer than the Mets’ total of 247 runs. The Cubs (350), Nats (319) and Giants (303) ranked second, fourth and seventh, respectively.

Maybe the Mets feel the activation of Wheeler will help their rotation simply outlast the others over the long haul. The initial plan coming into the season was to move Bartolo Colon into the bullpen when necessary, but now that he’s 6-3 with a 3.01 ERA through his first 12 starts, he might force them to reconsider that blueprint.

“You better believe it,” Collins said. “When Zack Wheeler is ready to be a major-league pitcher again, there will be a pretty hefty discussion of what’s going to be best for us.”

In the meantime, the Mets are going to need another bat from somewhere. Travis d’Arnaud is expected to return Tuesday, but they remain in the market for another infielder. One intriguing possibility is their former homegrown star Jose Reyes, whom the Rockies designated for assignment Wednesday. The Mets earlier denied interest in Reyes, who is coming off a 52-game suspension for domestic-abuse allegations. But they seem to be taking a more wait-and-see approach, perhaps in the hope he won’t be traded and instead will be released at the end of the 10-day DFA period.

Reyes was described as a “long shot” by a source Saturday, so the door isn’t closed, mainly because his speed and athleticism is something the Mets sorely lack. Reyes had 15 stolen bases through his first 66 games last season — more than the Mets’ entire team (13) right now. If Reyes is released, the Rockies are on the hook for the remaining $41 million on his contract, and his new team will be responsible for only the prorated portion of the MLB minimum, roughly $277,000. Though Reyes has told people close to him he could play third base, the Mets likely would use him at second and move Neil Walker to third.

Not only is Reyes a minimal financial risk, he costs nothing in minor-league talent, which can’t be said for the A’s Danny Valencia, the Brewers’ Aaron Hill or the Padres’ Yangervis Solarte. The Mets have traded five pitchers since last July — including Jon Niese for Walker in December — and needed this month’s draft to restock the arms in the system.